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NTP Configuration for My Homelab

This setup provides secure and reliable time synchronization for my homelab using public NTP servers. It serves time to internal devices over LAN (eth1) and WireGuard VPN (wg0), while blocking unauthorized access.

If you're adapting this for your own network, you'll need to update interfaces and subnets—see below.

How It Works

  • Syncs with public NTP servers (pool.ntp.org).
  • Serves time only on my homelab network (eth1) and WireGuard VPN (wg0).
  • Blocks all other traffic for security.

Install

Slackware

Slackware comes pre-installed with ntpd, so no need to install it.

Place the ntp.conf configuration file at:

/etc/ntp.conf

Create the appropriate directories based on the ntp.conf configuration:

mkdir -p /var/lib/ntp/stats
mkdir -p /var/log/ntp

And assign correct permissions to said directories:

chown ntp:ntp /var/lib/ntp
chown ntp:ntp /var/log/ntp

And then start the ntpd service:

/etc/rc.d/rc.ntpd start

Configuration

1️⃣ Listening on the Right Interfaces

By default, NTP only listens on my LAN and WireGuard VPN:

interface ignore wildcard
interface listen eth1   # LAN interface
interface listen wg0    # WireGuard VPN

Restricting Access

By default, only devices on my LAN (10.0.11.0/24) and VPN (10.0.12.0/24) can sync time:

restrict 10.0.11.0 mask 255.255.255.0 limited kod nomodify notrap nopeer
restrict 10.0.12.0 mask 255.255.255.0 limited kod nomodify notrap nopeer

Update these subnets to match your LAN and VPN ranges.

Choosing Time Sources

By default, the config syncs from public NTP pool servers:

server 0.pool.ntp.org iburst
server 1.pool.ntp.org iburst
server 2.pool.ntp.org iburst
server 3.pool.ntp.org iburst

If you have a local or ISP-provided NTP server, replace these with its address.

Useful commands

After modifying the config, restart ntp:

Slackware:

/etc/rc.d/rc.ntpd restart

Fedora / Debian / Arch or any other distro with systemd:

systemctl restart ntpd

To check if its working:

ntpq -p

To see if NTP is listening only on the correct interfaces:

ss -tulpn | grep ntpd

Final Notes

  • This is built for my homelab, but you can adapt it by changing interfaces and subnets.
  • Make sure firewalls allow UDP 123 if NTP clients can't connect.